Setting device for cutter heads

ABSTRACT

To set the proper location of a cutting bit, an optical scanner directs an optical beam toward a screen. The scanner is mounted on a base frame. The cutting bit is mounted on a cutting head holder which is, in turn, mounted on a support stage, the latter being vertically adjustable on the base frame. The cutting head holder is adjustable relative to the support stage and the measuring point. The support stage carries three support bodies for the rear side of the cutter head holder.

The invention concerns a setting device for cutter heads with arotatingly mounted cutter head holder, a base support frame and anoptical scanning apparatus with a projection screen to detect theprofile of one cutting edge at a measuring point.

Setting devices of this type are used for the setting of cutter heads,in particular of multiple edge milling tools with individuallyadjustable cutting bits.

In known setting devices, the cutter head holder is mounted on arotatingly supported spindle, fixedly mounted on the frame. The opticalscanning apparatus is adjustable, so that the measuring point, whichcorresponds to the zero point of a graticule on the projection screen,may be brought into a definite initial position with respect to the axisof rotation of the cutter head.

The unavoidable rotational inaccuracy of the cutter head holding spindlehas a considerable effect on the rotating accuracy and the axial run-outaccuracy of the cutter head detected and scanned. In the case of axialrun-out accuracies of the order of magnitude of 0.001 mm, which is oftenrequired, these known setting devices no longer yield satisfactoryresults. Furthermore, the measuring point, in which simultaneously thesetting of the individual cutting bits must also be effected, isaccessible with difficulty only.

It is therefore the object of the invention to provide a setting deviceof the aforementioned type, whereby the axial runout error caused by aholder spindle or the like, is extensively avoided. Simultaneously, themeasuring point should be readily accessible for the adjustment ofcutting edges. The device should have a simple and stable configuration.

This object is attained according to the invention by the followingcharacteristics:

(a) the optical scanning apparatus is arranged in the base mountingframe stationarily with respect to the frame and with an approximatelyhorizontal direction of the optical beam;

(b) a holding stage is guided in the base frame in a height adjustablemanner;

(c) the rotatable cutter head holder is displaceable in the holdingpiece with respect to the measuring point;

(d) the holding stage carries three support bodies for the rear side ofthe cutter head.

The rotatable cutter head holder here serves only to determine theradial position of the cutter head and to make possible the rotatingmotion between the individual setting processes. The axial run-outsetting, which is increasing in importance in the adjustment of thecutter head and which has very accurate requirements, is determined notby the rotating accuracy and the axial run-out accuracy of the rotatablecutter head holder, but by the position of the three support bodies,resting against the rear side of the cutter head. This takes intoaccount the fact that this rear side of the cutter head forms thesupporting surface of the cutter head on the frontal surface of thesupport flange of the machine tool. The axial run-out accuracy of thecutter head is thus determined by the position of the edges with respectto the said rear side of the cutter head. The supporting of the rearside of the cutter head by three supporting bodies renders it possibleto sight the cutter head with a very high accuracy in the settingdevice, without a potential axial run-out error or rotating error of therotating cutter head holder affecting the axial run-out accuracy of thecutter head. A further increase in the accuracy and simplification ofthe configuration of the apparatus is obtained by the stationarymounting of the optical scanning apparatus. The necessary radial endaxial setting of the milling tool to be scanned in relation tn themeasuring point is effected by that the support stage is adjustable inheight in the base frame at least within the range of the measuringpoint and that the cutter head holder is displaceable with respect tothe support stage. The measuring point, at which the cutting bit settingis also accomplished, is located in a readily accessible position on thefront side of the setting device.

According to an especially advantageous form of embodiment of theconcept of the invention, it is provided that the rotatable cutter headholder and at least two of the three support bodies are guideddisplaceably in the support stage. This makes it possible in a verysimple manner and without interfering with accuracy, the resetting ofcutter heads with different diameters within a very large diameterrange, without the need for appreciably increasing the dimensions of thesetting device. The measuring point remains well accessible, as itremains at the same location in the instrument.

For adaptation to cutter heads of different thicknesses, different borediameters and/or different overall configurations (single piececonstruction or divided configuration with a support body and areplaceable cutter head ring), the rotating cutter head holder and/orthe support bodies may be interchangeable in a further development ofthe concept of the invention, wherein for example support bodies ofdifferent heights may be used.

Further advantageous embodiments of the inventive concept are the objectof the dependent claims.

The invention will become more apparent from the examples of embodimentshown in the drawing attached hereto.

In the drawing:

FIG. 1 shows a setting device for cutter heads in a top view;

FIG. 2 the device according to FIG. 1 in a longitudinal section,

FIG. 3 an enlarged partial section along the line III--III in FIG. 1,

FIG. 4 a view, partially in section, in the direction of the arrow IV inFIG. 3 and

FIG. 5 a partial section along the line V--V in FIG. 3,

FIG. 6 in a simplified perspective view a modified form of embodiment inwhich the support stage is supported on three vertical height adjustingdevices, which may be actuated together and

FIG. 7 in a section similar to that of FIG. 2, a further form ofembodiment, in which the threaded spindle for the adjustment of theforward displacement of the lock rail is protruding from the settingdevice and is carrying the associated adjusting wheel.

The setting device for cutter heads has an essentially box shaped basemounting frame 1, which carries on its top side an optical scanningapparatus. The optical scanning apparatus comprises a projection lightsource 2, mounted on the frontal side of the device and emitting a beamof light 3 indicated in FIG. 1 by a dot-and-dash line and passing ameasuring point 4, whereupon it impacts a projection screen 6 afterdeflection by mirrors or prisms 5, said screen 6 being arranged over thebase frame 1. The projection screen 6 carries a graticule (not shown).On the projection screen 6, the profile of a milling cutter bit 7 isreproduced; it is then located at the measuring point 4. The enlargementof the projection is for example 50x.

On the upper side of the base frame 1, an approximately triangularsupport stage 8 is pivotingly supported in two bearing points 9, withthe connecting line of the two bearing points 9 forming the horizontalpivoting axis of the support stage 8. Under the measuring point 4, thesupport stage 8 is resting on a height adjusting device 10, which shallbe explained in more detail hereinbelow with reference to FIG. 3.

A lock rail 12 is guided in a slot 11 of the support stage 8 extendingin the direction of the light beam 3. As seen in FIG. 5, the lock rail12 engages with lateral projections 13 the bottom side of the supportstage 8. Guide beads 14 mounted on the support stage 8 engage thelateral projections 13 of the lock rail 12. A bearing plate 15 is beingpressured by means of screws 16 screwed into the lock rail 12 and springwashers 17 from below against the beads 14.

The lock rail 12 has a longitudinal T groove 18, in which a T shapedblock 19 is located. A screw 20 screwed into the clamping block 19fastens a bearing body 21 in any position chosen on the lock rail 12(FIG. 3 and 4). A rotatable cutter head holder 22 is rotatingly mountedon the bearing body 21. On its outer side, the rotatable cutter headholder 22 has a short cylindrical or spherical section 23 which fitsinto the bore of a cutter head 24 to be mounted; the latter is indicatedin FIG. 1, 2 and 3 by a dash-and-dot line.

A support body 25 is arranged on the front end of the lock rail 12,adjacently to the cutter head holder 23. Two further support bodies 25may be displaced in grooves 26 of the support stage 8, arranged radiallywith respect to the measuring point 4 and at an angle in relation toeach other, said support bodies being clampable in said grooves. In FIG.1, the arrangement of the support bodies 25 and the cutter head holder23 is shown for a cutter head 24 of the smallest possible diameter. Thelargest possible diameter of a cutter head to be mounted is indicated inFIG. 1 by a dash-and-dot line 24'. It is seen that the measuring point 4is unchanged for all cutter head diameters.

A threaded nut 27 is fastened to the under side of the lock rail 12(FIG. 2), which engages an adjusting threaded spindle 28 located underthe support stage 8. The threaded spindle 28 is supported in a bearing29 on the support stage 8 and is connected by means of a belt drive 30with an adjusting shaft 31 bearingly supported in the base frame 1 andleading to an adjusting hand wheel 32 on the frontal side of the device.The threaded nut 27 is further elastically supported on an abutment 34joined with the support stage by means of a compression spring 34. Byrotating the hand wheel 32, by means of the threaded spindle 28, aradial displacement of the lock rail 12 and thus of the cutter headholder 23, is obtained.

The device 10 for the adjustment in height of the support stage 8 has anadjusting hand wheel 35 accessible from the front side of the device,said hand wheel being supported on the base frame 1 by means of axialbearings 26. By means of a feather key 37, the hand wheel 35 isconnected rotatingly with a threaded bushing 38, which is engaging athreaded nut 39 mounted on the frame. At the upper end of the threadedsleeve 38, a bearing ball 40 supports a bridge 41, which is joined byscrewing on either side of the slot 11 to the support stage 8 (FIG. 4).

A center screw 42 clamps the bridge 41 by means of an adjusting ring 43and a compression spring 44 to an abutment 45 mounted on the frame,thereby maintaining the ball 40 in engagement with the associatedbearing surface on the upper end of the threaded sleeve 38.

To establish a zero setting for different cutter heads initially anannular gauge is placed onto the rotatable cutter head holder 22, whichmay be replaced to adapt it to different bore diameters, by releasingthe screw 20.

By means of the hand wheels 32 and 35, the radial and height settingsare effected until the edge of the gauge corresponding to the edge ofthe cutter head is located at the measuring point 4, i.e. until saidedge is reproduced in the zero point of the graticule on the projectionscreen 6. The apparatus is now calibrated for this height and thisdiameter and the gauge is removed.

Subsequently, the cutter head to be set is inserted so that it isabutting with its rear side against the three support bodies 25 and isaccepted with its bore on the section 23 of the cutter head holder 22.The cutter head is now rotated on the cutter head holder 22, until thefirst cutter edge to be set is in the optical focusing range. Thesetting of the bit edge is then effected so that the cutter edges to beset are in the desired position in relation to the graticule of theprojection screen 6. Finally, the cutter head is rotated until the nextedge to be set appears focused on the projection screen 6.

For the setting of certain predetermined edge angles, the graticule maybe mounted on the screen in a rotating manner. It is further possible toprovide additional lines adjacent to the graticule, provideinterchangeable projection screens or to mount different foilsinterchangeably on the projection screen 6.

As indicated in FIG. 1 and 2, the pivoting bearings of the support stage8 may consists of spherical bearings, but it is also possible to equipone or both of these bearings with cylindrical bearing bodies.

The support bodies 25 are preferably mounted interchangeably on thesupport stage 8 or the lock rail 12, respectively; they are replaced bysupport bodies of different heights, if a cutter head with a differentthickness is to be mounted. Similarly, the rotating cutter head holder22 is readily replaced in order to achieve adaptation to differentcutter head bore and different dimensions of the cutter heads to bemounted.

FIG. 6 shows a form of embodiment modified with respect to theembodiment of FIG. 1-5. The support stage 8 is resting here on threeheight adjusting devices 10', each of which has a threaded spindle 46.The threaded spindle 46 is connected by means of a supporting block 47at the two rear supports of the support stage 8 and the bridge 41 withthe support stage 8.

All three threaded spindles 46 engage a wheel 48 provided with internalthreads, said wheel being mounted in the base frame rotatingly, butstationarily in the axial direction. All three wheels 48 are connectedwith each other by means of a drive without play, for example a toothedbelt 49 or a chain. The wheel 48 located on the front side of themachine is connected with the adjusting hand wheel 35. If the hand wheel35 is rotated, all three wheels 48 are turned synchronously so that allof the threaded spindles 46 are screwed uniformly upwards or downwards,in order to uniformly raise or lower the support stage 8. For the sakeof simplified representation, in FIG. 6 the rotating cutter head holder22 and the support bodies 25 are eliminated.

FIG. 7 shows a modification with respect to the adjusting drive for thelock rail 12. The threaded spindle 28', engaging the threaded nut 27mounted on the lock rail 12, is in this form of embodiment in the bridge41' in an axial bearing and extends forward from the front side of thesetting device. There, the threaded spindle 28' carries the adjustinghand wheel 32'. The belt drive 30 and the adjusting shaft 31 of theembodiment according to FIG. 1-5 are eliminated.

I claim:
 1. Setting device for cutter heads with a rotatably supportedcutter head with a base mounting frame and an optical scanning apparatusdetecting the profile of a bit edge at a measuring point and beingprovided with a projection screen, the improvement wherein(a) theoptical scanning apparatus is arranged stationarily on the base frame,with an approximately horizontal direction of the optical beam; (b) asupport state is guided in the base frame in a height adjustable manner;(c) means provided for adjusting the height of the support stage; (d)the rotatable cutter head holder is displaceable in the support stage inrelation to the measuring point; and (e) three support bodies for therear side of the cutter head are carried by the support stage. 2.Setting device according to claim 1, characterized in that a pivotalmounting mounts the support stage for pivotal movement around ahorizontal axis located at a distance from the measuring point. 3.Setting device according to claim 2, characterized in that the supportstage is connected below the measuring point to the height adjustingdevice.
 4. Setting device according to claim 1, characterized in thatthe rotatable cutter head holder and at least two of the three supportbodies are guided displaceably in the support stage.
 5. Setting deviceaccording to claim 4, characterized in that a lock rail is adjustablymounted in the support stage, an adjusting drive for adjusting the lockrail relative to the support stage and relative to the measuring point,the rotatable cutter head holder being displaceably mounted in the lockrail, and a clamp means for clamping the cutter head holder in adjustedpositions in the lock rail.
 6. Setting device according to claim 5wherein the adjusting drive comprises a threaded adjusting spindlemounted on the support stage, a nut threadedly mounted on the lock railand carried by the adjusting spindle, an adjusting shaft, and a beltdrive operably connecting the adjusting shaft with the adjustingspindle.
 7. Setting device according to claim 6, characterized byremovable mounting means for mounting the rotatable cutter head holder.8. Setting device according to claim 1, characterized by removablemounting means for mounting the support bodies.
 9. Setting deviceaccording to claim 1, characterized in that the means for adjusting theheight of the support stage comprises three height adjusting devicesactuated together.
 10. Setting device according to claim 5,characterized in that the adjusting drive for the lock rail comprises athreaded adjusting spindle mounted on the support stage, a nutthreadedly carried by the adjusting spindle and connected to the lockrail, the adjusting spindle carrying a manual adjusting wheel. 11.Setting device according to claim 3, wherein the height adjusting devicecomprises a threaded adjusting sleeve.